The present invention relates to the field of the furniture industry. It concerns a device for lumbar support for an office swivel chair whose back of the seat is formed of a seatback frame having a membrane stretched over it.
These days people complain increasingly about back pain. Because of less movement and greater mental stress, such as constant stress, the motive apparatus becomes sluggish and atrophies, the muscles become fatigued and cramped, and circulation in tissue and organs becomes poor. Often the spinal column, as a sensitive and heavily stressed body part, must pay this price with pains and problems.
One seeks to counteract this, for example, by using special devices for lumbar support, such as lumbar pads, which are integrated into the seatback of office chairs. The curvature of the spinal column to the front (hollow back) is characterized as lordosis. The device for lumbar support is expected to fill in the hollow area in this case as precisely as possible.
Known are effective lumbar supports that are used in chairs having an additional seatback pad are (e.g. New York model of the applicant).
However, the currently known solutions for office chairs having a seatback with membrane covers without a seatback pillow are unsatisfactory.
On the one hand, these known devices for lumbar support on office chairs having a seatback with a membrane cover press in part uncomfortably against the user, even if they are soft or padded, as is the case, for example, with the Aeron model of the Herman Miller Company. In that case, a height adjustable lumbar pad is used with two guiding slots in the seatback frame.
On the other hand, the chairs having a seatback with a membrane cover, there are also earlier models having support devices that lead only to a barely noticeable lumbar support, e.g., Wilkhahn Modus and Vitra Meda Chair 2.
This unsatisfactory earlier state of the art results from the following problem: A back rest padded with foam permits placing a plastic element between the upholstery plate and the foam material that can be adjusted in height to suit the individual and which bows the pad forward to the position at which it supports the lumbar area of the user in question The pad itself ensures that the plastic element does not create pressure. Finally, the plastic element is upholstered just like the rest of the seatback. The pad substantially balances the structure.
A seatback having a membrane stretched over it without a pad structure, by contrast, does not show any upholstery covering the plastic element. Therefore, a device for lumbar support arranged behind or in front of the membrane and permanently inserted in the seatback frame independent of the membrane presses uncomfortably into the back, even if it is soft or padded.
If, by contrast, the lumbar support is not inserted in the seatback, but is inserted directly in the membrane, then it will move back along with the membrane and is, therefore, nearly without effect as a rule regarding relief of stress on the spinal column.
The present invention attempts to avoid the cited disadvantages of the known state of the art. It is based on the objective of developing a device for lumbar support for an office chair having a back rest that is formed of a seatback frame with a membrane stretched over it, the lumbar support being easily adjustable in height, not putting pressure on the user of the chair and at the same time supporting the lumbar area in a manner effective for the individual.
According to the invention, this objective is achieved by a device for lumbar support for an office chair according to the definition of the preamble to claim 1, wherein the device is adjustable in height and is also horizontally extendable. The lumbar pad position adjustment is embedded in the seatback frame independently of the membrane, but has sufficient elasticity for the pad not to create pressure. It is appropriate that the device consist of the following parts:
a) A central component having two comparatively rigid carrier elements that are connected to each other via an elastic element arranged in the center and each of which has on the outside a lateral guide stem, wherein the guide stems being arranged in the seatback frame and has a sliding adjustment,
b) a cushion pad as a front part arranged facing the membrane and fastened to an upholstery plate, as well as
c) a plastic plate as a back part, whereby
d) the cushion and the plastic plate, are connected via a clip connection and the clip connection is controlled in the guiding slots of the carrier elements.
Furthermore, it is practical if the elastic element is a rubber strap. This yields under a load sufficiently enough and effects the extension of the carrier elements so that the device, in particular the upholstery pillow, moves rearward. Consequently, there is no unduly high counter-pressure.
Additionally, it has its advantages, wherein the guiding frame of the carrier elements are each located in a guiding slot of the seatback frame, and/or on a guiding frame of the seatback frame. In this way, a simple guide and height adjustment of the device for lumbar-support is possible. That results in an exact tracking of the pad corresponding to the membrane.